Plenty of smartphones are now offering “3D” or “virtual 5.1 surround” experiences, but what exactly does that mean? While you won’t get theater-quality sound out of tiny smartphone speakers, various processing options are now available that can make your phone’s aural performance a little more impressive.

SRS Labs has licensed its processing algorithms to manufacturers like Motorola, Samsung, and HTC. They go by many names, including SRS 5.1 Mobile, WOW HD, and the latest, WideSurround. While the precise ways these systems process sound may differ, the result is that you get something that sounds “bigger” than straight-up stereo playback.

What’s actually going on behind the scenes? While stereo sound is an easy enough concept to grasp, things get trickier when you go into three dimensions. How can you tell if a sound is coming from directly in front of you, overhead, or behind? After all, in all three cases the source would be equidistant between your ears. The shape of your head and ears introduces subtle timing differences in the sounds you hear that let your brain figure out where they’re coming from. After careful study of how humans hear what we do, engineers can create algorithms that can simulate those same timing differences that let us gauge the direction sound comes from.

Some of these virtual surround systems just use these acoustic tricks to make a standard stereo recording sound like one coming from bigger and better speakers. Besides making you hear noises emanating from where there’s no speaker, certain systems can trick you into hearing sounds that small smartphone speakers might not be able to produce on their own, increasing the perceived frequency range. Others actually try to simulate a discrete 5.1-channel speaker setup.

The 3D sound setting may be hidden away in a menu, but try flipping it on if your phone supports it and giving a listen. Do the processing algorithms actually deliver, or do you prefer the simplicity of plain-old stereo?